the case of guided missiles, which are connected with a ground facility by means of a beam waveguide, it is known to carry out a real-time picture transmission by means of a camera. In addition to the picture data, as a result of the high bandwidth, measuring values of the instrumentation are at the same time transmitted by way of the beam waveguide from the guided missile FK to the ground facility as well as, in the opposite direction, the required control and switching commands for the guiding of the guided missile are transmitted from the ground.
It is the purpose of constructions of this type that the person firing the missile, by means of the TV camera for daytime viewing or the IR camera for nighttime viewing, can navigate the guided missile FK into a specified target area and there can detect, recognize, identify and combat targets existing there. Since the flight into the target area takes place mainly according to map information with a simultaneous support by the gyroscopes, a field of view which is as large as possible is advantageous for the purpose of orientation during navigation because it increases the chances of detecting prominent points in the terrain.
Tests have shown that, in the Central European terrain at flight altitudes between 150 m and 250 m, prominent structures of the terrain--such as roads, rivers, forests, buildings, etc. --can be recognized at distance ranges of from 3 to 7 km, and a width of the field of view of approximately 1,500 m in the case of a distance of 5 km or 1,000 m in the case of a distance of 3 km is sufficient for the purpose of orientation. In the case of a 2/3-inch target--thus a CCD-array of a diagonal length of 11 mm--this corresponds to a focal length of an objective of approximately 28 mm.
However, the person firing the missile, for an early target recognition and identification, requires relatively large coverages which naturally can be reached easily only by means of long focal lengths of the objective and offer correspondingly small and clear fields of view. In the case of the above-mentioned target or CCD-array, this means that the focal length would have to be longer than 80 mm in which case, however, in the case of long focal lengths, the stabilizing quality of the camera must be taken into account and finally determines the limits of the selection of the focal length.
In this respect, it has been suggested that a compromise be made for the two tasks--navigation and early target recognition --and a mean focal length of 50 mm be selected. This means, however, that, for being sufficiently successful, the two tasks can be solved only in extremely good viewing conditions, with a person firing the guided missile who is highly trained with respect to map navigation and target recognition and who reacts quickly.
In order to ensure that the mission is carried out successfully also in worse viewing conditions, for example, in high atmospheric humidity and with a hazy view, or at dusk or dawn, or under rainy or dusty conditions, it has been suggested to use a motor-driven zoom objective with a focal length of 28 to 100 mm. However, the results were not as good as expected because a zoom objective of this type not only requires a relatively large amount of space, it is also heavy and expensive and--which is important--much too slow with respect to its use. Furthermore, this type of an objective, in the case of changes of the focal length, also has corresponding changes of length and thus shifts of the center of gravity which results in considerable problems with respect to the integration on the stabilizing platform.
Also, additional devices are required in this case--such as position indicators--for informing the picture tracker and the guiding computer in the ground facility concerning the respective adjusted enlarging factor of the picture, since picture displacements enter the guiding law as angular rotations, and the angular rotation is a function of the enlarging factor.
It is an object of the present invention to provide a device of the initially mentioned type which is free of the above-mentioned disadvantages of the state of the art and ensures a real-time picture transmission which changes over extremely fast from one picture to the next, requires no focussing and axis harmonization during the mission and for the change-over no longer has any mechanically movable parts in the camera.
This object is achieved according to preferred embodiments of the invention by means of an arrangement for the real-time picture transmission in the case of a guided missile (FK) which is connected with a ground guiding station by way of a beam waveguide, wherein the picture transmission takes place by means of a camera arranged on a platform and having objectives of different focal lengths, wherein the camera is constructed as a double focal length camera in which partial lens systems for a short focal length and a long focal length form a single structural double lens system member, the lens part for the short focal length being integrated in the center of the lens part for the long focal length, wherein picture arrays assigned to both focal lengths are arranged on a common support, the overall length of the long focal length being shortened, by means of a reflecting mirror, and wherein only one electronic camera system for both picture arrays is arranged with an electronic changeover to the respective required focal length.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.